A magnetic encoder implementation method and magnetic encoder adapted to shaft movement

Abstract

The present application relates to the field of encoders, and in particular to a method for implementing a magnetic encoder that is adaptable to shaft movement, which specifically includes the following steps: sensing the change in magnetic field strength of a magnet based on an angle detection element provided on a resolver board to obtain a measured angle value θa of the rotation of a shaft to be measured; detecting the axial movement of the magnet along the shaft to be measured based on an axial displacement detection element provided on the resolver board to obtain a movement value L; obtaining a compensation value θe based on the movement value L; and compensating the compensation value θe to the measured angle value θa. The angle value θm finally output by the compensated encoder is expressed as: θm=θa+θe, so that when the shaft to be measured undergoes axial movement, the detection result is less likely to deviate, thereby improving the accuracy of the detection result.

Description

Technical Field

[0001] The present application relates to the field of encoders, and in particular to a method for implementing a magnetic encoder that is adaptable to shaft runaway and a magnetic encoder. Background Art

[0002] Encoders are high-precision devices used to detect the rotational angle of rotating objects, such as the rotation angle of a motor shaft on a high-precision machine tool. Magnetic encoders have various structures and implementation principles. One such encoder uses a magnet that rotates synchronously with the shaft being measured and uses a magnetic sensor to detect changes in the rotating magnet's magnetic field. A resolver then calculates the magnet's rotational angle, effectively the shaft's rotational angle.

[0003] Existing magnetic encoders are mechanically classified into two types: those with built-in bearings and those without. Compared to encoders with built-in bearings, encoders without built-in bearings offer advantages such as space savings, high shaft speeds, no additional starting torque, and a service life not limited by bearing life.

[0004] Regarding the above-mentioned related technologies, the shaft to be measured without built-in bearings will inevitably shake during rotation, especially the movement along the axis of the shaft to be measured itself. When the shaft to be measured has axial movement, the distance between the magnet and the magnetic induction device will change. The greater the distance between the magnet and the magnetic induction device, the smaller the amplitude of the original signal output by the magnetic induction device, and the lower the accuracy of the final detection result. Summary of the Invention

[0005] In order to reduce the impact of axial movement of a shaft to be measured on the accuracy of the angle detection result of the shaft to be measured, the present application provides a method for implementing a magnetic encoder that is adaptable to axial movement and a magnetic encoder.

[0006] In a first aspect, the present application provides a method for implementing a magnetic encoder that is adaptable to shaft runaway, which adopts the following technical solution.

[0007] A method for implementing a magnetic encoder that adapts to shaft runaway specifically includes the following steps.

[0008] Step 1: The angle detection element provided on the solver board senses the change in magnetic field strength of the magnet rotor to obtain the measured angle value θa of the rotation of the shaft to be measured.

[0009] Step 2: Detecting the axial displacement of the magnet rotor along the axis to be measured using an axial displacement detection element provided on the solver board to obtain a displacement value L;

[0010] Step 3: Obtain the compensation value θe based on the drift value L;

[0011] Step 4: Add the compensation value θe to the measured angle value θa. The angle value θm output by the compensated encoder is expressed as: θm=θa+θe.

[0012] By adopting the above technical solution, during the operation of an encoder without a built-in bearing, the play value L can be obtained based on the axial displacement detection element, and the corresponding compensation value θe can be obtained based on the play value L, so that the measured angle value θa and the compensation value θe are added together for compensation, making the final output angle value θm less likely to deviate due to the axial play of the detection shaft, thereby improving the accuracy of the detection results.

[0013] Optionally, the method for obtaining the jitter value L is that the axial displacement detection element senses the change in magnetic field strength of the magnet and outputs an analog signal, and the analog signal is converted into a digital jitter value L by the analog-to-digital conversion module.

[0014] Optionally, the method for obtaining the measured angle value θa is that the angle detection element receives the change in magnetic field strength of the magnet and outputs an analog signal, and the analog-to-digital conversion module converts the analog signal into an angle digital signal and solves it to obtain the measured angle value θa.

[0015] By adopting the above technical solution, the magnetic field change of the magnet rotor is detected to obtain the rotation angle and axial movement degree of the magnet rotor, and the rotation angle and axial movement degree of the shaft to be measured are obtained in turn.

[0016] Optionally, the method for obtaining the compensation value θe in step 3 is to obtain the ideal angle value θb, obtain the functional relationship P(L) based on the three groups of data of the ideal angle value θb, the measured angle value θa and the drift value L, and pre-store P(L) in the memory so that after the drift value L is obtained, the functional relationship P(L) can be called to obtain the compensation value θe.

[0017] By adopting the above technical solution, the compensation value θe can be obtained in real time according to the oscillation value L by only obtaining the corresponding functional relationship between the compensation value θe and the oscillation value L.

[0018] Optionally, the method for obtaining the functional relationship P(L) is to obtain multiple sets of ideal angle values ​​θb, measured angle values ​​θa and drift values ​​L based on multiple experiments or simulation calculations, obtain a compensation data table with the drift value L as a variable and the compensation value θe as a dependent variable, and store the compensation data table as P(L).

[0019] By adopting the above technical solution, there is no need to obtain a specific functional relationship P(L). It is only necessary to obtain the unique corresponding drift value L and compensation value θe under different drift amounts of the magnet rotor and prepare a corresponding compensation data table. The compensation data table is stored to extract the compensation value θe in real time after the drift value L is obtained.

[0020] In a second aspect, the present application provides a magnetic encoder that adopts the following technical solution.

[0021] A magnetic encoder uses the above-mentioned method for implementing a magnetic encoder that adapts to shaft movement to detect the rotation angle of a shaft to be measured, comprising a housing, a resolver board arranged on the housing, a magnet rotor coaxially fixedly connected to the shaft to be measured, an angle detection element arranged on the resolver board and detecting the rotation angle of the magnet rotor, and an axial displacement detection element arranged on the resolver board and detecting the amount of axial movement of the magnet rotor along the axial direction of the shaft to be measured. The angle detection element and the axial displacement detection element are both connected to a signal processing unit of the resolver board.

[0022] By adopting the above technical solution, while the angle detection element detects the rotation angle of the magnet rotor, the axial displacement detection element can simultaneously detect the axial movement of the magnet rotor, so that the solver board can compensate the detected rotation angle of the magnet rotor in real time according to the degree of axial movement of the magnet rotor, making the measured shaft rotation angle value finally output by the solver board more accurate.

[0023] Optionally, the axial displacement detection element includes an axial linear Hall sensor.

[0024] Optionally, the angle detection element includes two radial linear Hall sensors.

[0025] Optionally, a plurality of the angle detection elements are provided, and the two radial linear Hall sensors of each angle detection element are distributed opposite each other with the axis of the shaft to be measured as the center line.

[0026] By adopting the above technical solution, two angle detection elements are arranged facing each other to form a differential signal, thereby removing filtering interference, and multiple angle detection elements help to improve the accuracy of the rotation angle of the magnet rotor.

[0027] In summary, this application has at least one of the following beneficial effects:

[0028] 1. During the operation of an encoder without an internal bearing, the axial displacement detection element can be used to obtain the play value L. Based on this play value L, the corresponding compensation value θe is obtained. The measured angle value θa and the compensation value θe are added together for compensation. This makes the final output angle value θm less susceptible to deviation due to axial play of the detection shaft, thereby improving the accuracy of the detection results.

[0029] 2. There is no need to obtain the specific functional relationship P(L). It is only necessary to obtain the unique corresponding drift value L and compensation value θe under different drift amounts of the magnet rotor and make a corresponding compensation data table. The compensation data table is stored so that the compensation value θe can be extracted in real time after the drift value L is obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a flowchart of a method for implementing a magnetic encoder that is adaptable to shaft drift in an embodiment;

[0031] Figure 2 1 is a schematic diagram of the overall structure of the magnetic encoder in Example 1;

[0032] Figure 3 It is a schematic diagram of the overall structure of the magnetic encoder in Example 2.

[0033] Explanation of the accompanying reference numerals: 1. housing; 2. shaft to be measured; 3. magnet rotor; 31. resolver plate; 32. angle detection element; 33. axial displacement detection element; 34. notch. DETAILED DESCRIPTION

[0034] The present application is further described in detail below with reference to the accompanying drawings.

[0035] Example 1:

[0036] The first embodiment of the present application discloses a method for implementing a magnetic encoder that adapts to shaft movement, referring to Figure 1 , specifically including the following steps.

[0037] Step 1: The angle detection element 32 provided on the resolver board 31 senses the change in the magnetic field strength of the magnet rotor 3 to obtain the measured angle value θa of the rotation of the shaft 2 to be measured.

[0038] Step 2: Detect the axial displacement of the magnet rotor 3 along the shaft 2 to be measured using the axial displacement detection element 33 provided on the resolver board 31 to obtain the displacement value L;

[0039] Step 3: Obtain the compensation value θe based on the drift value L;

[0040] Step 4: Add the compensation value θe to the measured angle value θa. The angle value θm output by the compensated encoder is expressed as: θm=θa+θe.

[0041] The specific process for measuring the angle value θa in step 1 is as follows: the angle detection element 32 receives the magnetic field signal from the magnet rotor 3 and outputs an analog angle signal. The analog-to-digital conversion module converts the analog angle signal into a digital angle signal a. The angle value θa is then calculated based on the changing functional relationship of the digital angle signal a. The specific process for determining the play value L in step 2 is as follows: the axial displacement detection element 33 receives the magnetic field signal from the magnet and outputs an analog distance signal. The analog-to-digital conversion module converts the analog distance signal into a digital play value L.

[0042] In order to obtain the compensation value θe in step 3, it is necessary to first obtain the array of ideal angle values ​​θb, measured angle values ​​θa and corresponding jitter values ​​L. Since there is a corresponding functional relationship between the three, that is, θb-θa=P(L)=θe, and P(L) represents the functional relationship of obtaining the corresponding compensation value θe from the jitter value L, and in order to obtain P(L), it is necessary to obtain the compensation value θe corresponding to each jitter value L based on multiple sets of ideal angle values ​​θb, measured angle values ​​θa and corresponding jitter values ​​L obtained by experiments or simulation calculations, and then obtain a compensation data table with the jitter value L as a variable and the compensation value θe as a dependent variable, and store the compensation data table as P(L) for use. The corresponding compensation value θe can be extracted from the compensation data table based on the jitter value L obtained in real time to compensate for the measured angle value θa.

[0043] In the process of obtaining the compensation data table, the method for obtaining the ideal angle value θb and the measured angle value θa can be as follows: prepare two magnetic encoders with the presence or absence of built-in bearings as the only variable, and the two magnetic encoders work synchronously corresponding to the same measured shaft 2. The magnetic encoder with built-in bearings outputs the ideal angle value θb, and the magnetic encoder without built-in bearings outputs the measured angle value θa. The two magnetic encoders can synchronously output a corresponding play value L, and the play value L output by the magnetic encoder with built-in bearings remains unchanged to ensure that the ideal angle value θb output by the magnetic encoder with built-in bearings is the rotation angle value of the measured shaft 2 under ideal conditions without the influence of axial play. The play value L output by the magnetic encoder without built-in bearings needs to be recorded synchronously each time a set of ideal angle values ​​θb and measured angle values ​​θa are recorded.

[0044] In other implementations of this embodiment, in order to obtain the compensation value θe corresponding to different play values ​​L, a magnetic encoder with an adjustable axial distance between the angle detection element 32 and the magnet rotor 3 and another high-precision magnetic encoder (i.e., a reference encoder) can also be provided and coaxially fixedly connected. When the axial distance between the angle detection element 32 and the magnet rotor 3 is different, the angle difference output by the two magnetic encoders is the compensation value θe.

[0045] The implementation principle of a magnetic encoder implementation method that adapts to shaft movement in embodiment 1 of the present application is: obtaining a corresponding compensation value θe based on the movement value L that reflects the axial movement of the shaft 2 to be measured, so as to compensate for the measured angle value θa that has a certain error due to the influence of the axial movement of the shaft 2 to be measured, so that the final output angle value θm is closer to the ideal rotation angle of the shaft 2 to be measured that is not affected by the axial movement, thereby improving the accuracy of the detection result of the rotation angle of the shaft 2 to be measured.

[0046] The first embodiment of the present application also discloses a magnetic encoder, referring to Figure 2, including a shell 1, a resolver plate 31 is fixedly connected to the inner circumferential wall of the shell 1, the resolver plate 31 can be made into a ring shape or a circle shape according to needs, a magnet rotor 3 with the same axis is provided on one side of the resolver plate 31, the magnet rotor 3 is annular, and the magnet rotor 3 is coaxially fixed to the outer circumferential wall of the end of the shaft to be measured 2, and the magnet rotor 3 can be magnetized in a single pole, two poles, multiple poles or horizontally and radially according to needs.

[0047] In other implementations of this embodiment, the magnet rotor 3 may be coaxially fixed with a disc holder, and the disc holder and the shaft to be measured 2 may be detachably connected via bolts so that the shaft to be measured 2 and the magnet rotor 3 can be separated.

[0048] Reference Figure 2 Angle detection elements 32 are evenly fixedly connected to the resolver board 31 around the axis of the magnet rotor 3. Each angle detection element 32 includes two radial linear Hall sensors arranged in a diametrically opposed relationship with the axis of the magnet rotor 3 as the centerline, forming a differential signal and eliminating filtering. The process of obtaining the angle digital signal a from the angle detection element 32 is as follows: the two radial linear Hall sensors receive the magnetic field signal from the magnet rotor 3 and output a corresponding angle analog signal. The analog-to-digital conversion module on the resolver board 31 converts the angle analog signals output by the two radial linear Hall sensors into two angle digital signals a+ and a-. The signal processing unit of the resolver board 31 ultimately outputs the angle digital signal a = a+ / a-. In this embodiment, three angle detection elements 32 can be evenly arranged around the axis of the magnet rotor 3, and the resolver board 31 obtains the corresponding angle digital signal a according to the corresponding calculation formula.

[0049] Reference Figure 2 The resolver board 31 is fixedly connected to an axial displacement detection element 33, which can be an axial linear Hall effect sensor. A constant distance exists between the axial displacement detection element 33 and the end surface of the magnet rotor 3 along the axis of the magnet rotor 3. The axial displacement detection element 33 is located on one side of the end surface of the magnet rotor 3, enabling it to smoothly detect the axial movement of the magnet rotor 3. Both the angle detection element 32 and the axial displacement detection element 33 are connected to the signal processing unit of the resolver board.

[0050] The implementation principle of a magnetic encoder in the first embodiment of the present application is as follows: the angle detection element 32 detects the rotation angle of the magnet rotor 3 so that the resolver 31 calculates and obtains the measured angle value θa; the axial displacement detection element 33 detects the degree of axial movement of the magnet rotor 3 so that the resolver 31 calculates and obtains the movement value L; the resolver 31 extracts the corresponding compensation value θe based on the movement value L and through the compensation data table stored in the memory of the resolver 31; the resolver 31 compensates the compensation value θe to the measured angle value θa to finally output the angle value θm.

[0051] Example 2:

[0052] The second embodiment of the present application discloses a magnetic encoder, which is different from the first embodiment in that: Figure 3 A notch 34 is coaxially provided on the end face of the shaft 2 to be measured. The magnet rotor 3 is circular and coaxially fixedly connected to the circumferential inner wall and bottom surface of the notch 34 . The magnet rotor 3 is completely located in the notch 34 .

[0053] The implementation principle of a magnetic encoder in the second embodiment of the present application is as follows: the size of the magnet rotor 3 is smaller, and the corresponding sizes of the resolver board 31 and the housing 1 can also be reduced, so that the overall volume of the magnetic encoder becomes smaller.

[0054] The above are all preferred embodiments of the present application, and are not intended to limit the scope of protection of the present application. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the scope of protection of the present application.

Claims

1. A method for implementing a magnetic encoder that adapts to shaft movement, characterized by: The specific steps include: Step 1: The angle detection element (32) provided on the solver (31) senses the change in the magnetic field strength of the magnet rotor (3) to obtain the measured angle value θa of the rotation of the shaft to be measured (2). Step 2: Detecting the axial displacement of the magnet rotor (3) along the axis to be measured (2) based on the axial displacement detection element (33) provided on the solver plate (31) to obtain the displacement value L; Step 3: Obtain the compensation value θe based on the drift value L; Step 4: Add the compensation value θe to the measured angle value θa. The angle value θm output by the compensated encoder is expressed as: θm=θa+θe.

2. The method for implementing a magnetic encoder adapted to shaft movement according to claim 1, characterized in that: The method for obtaining the said oscillation value L is that the axial displacement detection element (33) senses the change in the magnetic field intensity of the magnet and outputs an analog signal, and the analog-to-digital conversion module converts the analog signal into a digital oscillation value L.

3. The method for implementing a magnetic encoder adapted to shaft movement according to claim 1, characterized in that: The method for obtaining the measured angle value θa is as follows: the angle detection element (32) receives the change in magnetic field intensity of the magnet and outputs an analog signal, and the analog-to-digital conversion module converts the analog signal into an angle digital signal and calculates and obtains the measured angle value θa.

4. The method for implementing a magnetic encoder adapted to shaft movement according to claim 1, characterized in that: The method for obtaining the compensation value θe in step 3 is to obtain the ideal angle value θb, obtain the functional relationship P(L) based on the three groups of data of the ideal angle value θb, the measured angle value θa and the drift value L, and pre-store P(L) in the memory so that after the drift value L is obtained, the functional relationship P(L) can be called to obtain the compensation value θe.

5. The method for implementing a magnetic encoder adapted to shaft movement according to claim 4, characterized in that: The method for obtaining the functional relationship P(L) is to obtain multiple sets of ideal angle values ​​θb, measured angle values ​​θa and drift values ​​L based on multiple experiments or simulation calculations, obtain a compensation data table with the drift value L as a variable and the compensation value θe as a dependent variable, and store the compensation data table as P(L).

6. A magnetic encoder for detecting the rotation angle of a shaft to be measured (2) based on the method for realizing a magnetic encoder adapted to shaft movement according to any one of claims 1 to 5, characterized in that: The invention comprises a housing (1), a resolver plate (31) provided on the housing (1), a magnet rotor (3) coaxially fixedly connected to a shaft to be measured (2), an angle detection element (32) provided on the resolver plate (31) and detecting the rotation angle of the magnet rotor (3), and an axial displacement detection element (33) provided on the resolver plate (31) and detecting the amount of movement of the magnet rotor (3) along the axial direction of the shaft to be measured (2). Both the angle detection element (32) and the axial displacement detection element (33) are connected to a signal processing unit of the resolver plate (31).

7. A magnetic encoder according to claim 6, characterized in that: The axial displacement detection element (33) includes an axial linear Hall sensor.

8. The magnetic encoder according to claim 6, characterized in that: The angle detection element (32) includes two radial linear Hall sensors.

9. A magnetic encoder according to claim 8, characterized in that: A plurality of the angle detection elements (32) are provided, and the two radial linear Hall sensors of each angle detection element (32) are distributed in a direction opposite to each other with the axis of the shaft to be measured (2) as the center line.

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